Standard multivitamin/multimineral tablets contain nutrients at levels believed to be safe for the majority of healthy people, as indicated by amounts at or below the recommended daily allowance. However, even these supplements could be harmful for people with certain diseases, such as kidney or liver disease, or for people taking certain medications, such as warfarin.

There are other multivitamin/multimineral tablets that contain high levels of certain nutrients far above nutritional needs. These could conceivably present risks for healthy people, particularly if they are taken in combination with additional specific supplements. Almost any mineral can be toxic if taken to excess, and there are also risks with excessive intake of vitamins A, B 6 , and D.